AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers

An optically activated, enhancement mode heterostructure field effect transistor is proposed and analytically studied. A particular feature of this device is its gate region, which is made of a photovoltaic GaN/AlN-based superlattice detector for a wavelength of 1.55 µm. Since the inter-subband tran...

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Autores principales:	Daniel Hofstetter, Cynthia Aku-Leh, Hans Beck, David P. Bour
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	GaN HEMT inter-subband transition telecommunication wavelength of 1.55 µm enhancement mode transistor Crystallography QD901-999
Acceso en línea:	https://doaj.org/article/174ff9195f664f5bb2edfabcce176fe6
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spelling	oai:doaj.org-article:174ff9195f664f5bb2edfabcce176fe62021-11-25T17:19:44ZAlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers10.3390/cryst111114312073-4352https://doaj.org/article/174ff9195f664f5bb2edfabcce176fe62021-11-01T00:00:00Zhttps://www.mdpi.com/2073-4352/11/11/1431https://doaj.org/toc/2073-4352An optically activated, enhancement mode heterostructure field effect transistor is proposed and analytically studied. A particular feature of this device is its gate region, which is made of a photovoltaic GaN/AlN-based superlattice detector for a wavelength of 1.55 µm. Since the inter-subband transition in this superlattice does normally not interact with TE-polarized (or vertically incoming) radiation, a metallic second-order diffraction grating on the transistor gate results in a re-orientation of the light into the horizontal direction—thus providing the desired TM-polarization. Upon illumination of this gate, efficient inter-subband absorption lifts electrons from the ground to the first excited quantized state. Due to partial screening of the strong internal polarization fields between GaN quantum wells and AlN barriers, this slightly diagonal transition generates an optical rectification voltage. Added to a constant electrical bias, this optically produced gate voltage leads to a noticeable increase of the transistor’s source-drain current. The magnitude of the bias voltage is chosen to result in maximal transconductance. Since such a phototransistor based on high-bandgap material is a device involving only fast majority carriers, very low dark and leakage currents are expected. The most important advantage of such a device, however, is the expected switching speed and, hence, its predicted use as an optical logic gate for photonic computing. In the absence of a p-n-junction and thus of both a carrier-induced space charge region, and the parasitic capacitances resulting thereof, operation frequencies of appropriately designed, sufficiently small phototransistors reaching 100 GHz are envisaged.Daniel HofstetterCynthia Aku-LehHans BeckDavid P. BourMDPI AGarticleGaNHEMTinter-subband transitiontelecommunicationwavelength of 1.55 µmenhancement mode transistorCrystallographyQD901-999ENCrystals, Vol 11, Iss 1431, p 1431 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	GaN HEMT inter-subband transition telecommunication wavelength of 1.55 µm enhancement mode transistor Crystallography QD901-999
spellingShingle	GaN HEMT inter-subband transition telecommunication wavelength of 1.55 µm enhancement mode transistor Crystallography QD901-999 Daniel Hofstetter Cynthia Aku-Leh Hans Beck David P. Bour AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers
description	An optically activated, enhancement mode heterostructure field effect transistor is proposed and analytically studied. A particular feature of this device is its gate region, which is made of a photovoltaic GaN/AlN-based superlattice detector for a wavelength of 1.55 µm. Since the inter-subband transition in this superlattice does normally not interact with TE-polarized (or vertically incoming) radiation, a metallic second-order diffraction grating on the transistor gate results in a re-orientation of the light into the horizontal direction—thus providing the desired TM-polarization. Upon illumination of this gate, efficient inter-subband absorption lifts electrons from the ground to the first excited quantized state. Due to partial screening of the strong internal polarization fields between GaN quantum wells and AlN barriers, this slightly diagonal transition generates an optical rectification voltage. Added to a constant electrical bias, this optically produced gate voltage leads to a noticeable increase of the transistor’s source-drain current. The magnitude of the bias voltage is chosen to result in maximal transconductance. Since such a phototransistor based on high-bandgap material is a device involving only fast majority carriers, very low dark and leakage currents are expected. The most important advantage of such a device, however, is the expected switching speed and, hence, its predicted use as an optical logic gate for photonic computing. In the absence of a p-n-junction and thus of both a carrier-induced space charge region, and the parasitic capacitances resulting thereof, operation frequencies of appropriately designed, sufficiently small phototransistors reaching 100 GHz are envisaged.
format	article
author	Daniel Hofstetter Cynthia Aku-Leh Hans Beck David P. Bour
author_facet	Daniel Hofstetter Cynthia Aku-Leh Hans Beck David P. Bour
author_sort	Daniel Hofstetter
title	AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers
title_short	AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers
title_full	AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers
title_fullStr	AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers
title_full_unstemmed	AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers
title_sort	algan-based 1.55 µm phototransistor as a crucial building block for optical computers
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/174ff9195f664f5bb2edfabcce176fe6
work_keys_str_mv	AT danielhofstetter alganbased155μmphototransistorasacrucialbuildingblockforopticalcomputers AT cynthiaakuleh alganbased155μmphototransistorasacrucialbuildingblockforopticalcomputers AT hansbeck alganbased155μmphototransistorasacrucialbuildingblockforopticalcomputers AT davidpbour alganbased155μmphototransistorasacrucialbuildingblockforopticalcomputers
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AlGaN-Based 1.55 µm Phototransistor as a Crucial Building Block for Optical Computers

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